226a318897
Use real GPIO pad inversion to allow inverted RX, TX, and controls for the hardware UART and software PIO-emulated serial ports. Adds ``setInvertTX(bool)`` and ``setInvertRX(bool)`` calls to both ports, with ``setInvertControl(bool)`` for the HW UARTS.
42 lines
1.7 KiB
ReStructuredText
42 lines
1.7 KiB
ReStructuredText
"SoftwareSerial" PIO-based UART
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================================
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Equivalent to the Arduino SoftwareSerial library, an emulated UART using
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one or two PIO state machines is included in the Arduino-Pico core. This
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allows for up to 4 bidirectional or up to 8 unidirectional serial ports to
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be run from the RP2040 without requiring additional CPU resources.
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Instantiate a ``SerialPIO(txpin, rxpin, fifosize)`` object in your sketch and then
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use it the same as any other serial port. Even, odd, and no parity modes
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are supported, as well as data sizes from 5- to 8-bits. Fifosize, if not
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specified, defaults to 32 bytes.
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To instantiate only a serial transmit or receive unit, pass in
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``SerialPIO::NOPIN`` as the ``txpin`` or ``rxpin``.
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For example, to make a transmit-only port on GP16
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.. code:: cpp
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SerialPIO transmitter( 16, SerialPIO::NOPIN );
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For detailed information about the Serial ports, see the
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Arduino `Serial Reference <https://www.arduino.cc/reference/en/language/functions/communication/serial/>`_ .
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Inversion
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---------
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``SoftwareSerial`` and ``SerialPIO`` can both support inverted input and/or outputs via the methods
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``setInvertRX(bool invert)`` and ``setInvertTX(bool invert)``.
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SoftwareSerial Emulation
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========================
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A ``SoftwareSerial`` wrapper is included to provide plug-and-play compatibility
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with the Arduino `Software Serial <https://docs.arduino.cc/learn/built-in-libraries/software-serial>`_
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library. Use the normal ``#include <SoftwareSerial.h>`` to include it. The following
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differences from the Arduino standard are present:
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* All ports are always listening
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* ``listen`` call is a no-op
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* ``isListening()`` always returns ``true``
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